An object of the disclosed invention is to provide a polling-based multihop communication system capable of achieving robust communication. Solving means thereof is a (multihop communication) wireless transmission system including, as wireless stations, a base station, a plurality of relay stations connected at multiple stages by using the base station as a root, and a plurality of terminals connected to the relay stations, in which the base station and the relay stations perform communication using polling in one or more service periods which have been allocated to each of the base and relay stations in time division in advance in a system cycle.
Legal claims defining the scope of protection. Each claim is shown in both the original legal language and a plain English translation.
1. A wireless transmission system, comprising: a base station, a plurality of relay stations, and a plurality of terminals as wireless stations, the terminals and the relay stations being wirelessly connected to the base station or the relay stations at multiple stages, wherein: the base station and the relay stations are synchronized, and a system cycle of the base station and a system cycle of the relay stations are the same in terms of time; one or more service periods are allocated in time division to the base station and the relay stations in the single system cycle; the base station or each of the relay stations includes means for performing polling communication with the terminal registered in own station with the use of polling in the single service period; in the polling communication, the base station or the relay station transmits a polling packet to the terminal registered in the own station, and the base station or the relay station includes means for receiving a reply signal from the terminal registered in the own station; and the base station and the relay station to which the service periods are allocated include means for transmitting an end notification packet when the service period ends, and means for causing the end notification packet to have transmission prohibition time information based on a polling period length of the polling communication of the base station or the relay station to which the next service period is allocated.
A wireless communication system uses a base station, multiple relay stations, and terminals. Relays and terminals connect wirelessly to the base station or other relays in a multi-hop fashion. The base station and relays are synchronized to the same system cycle time. Each base and relay station is pre-allocated one or more time-divided service periods within this cycle. Within its service period, each base or relay station polls its registered terminals, transmitting a polling packet and receiving a reply. After the service period, the base or relay transmits an end notification packet that includes transmission prohibition time information. This prohibition is based on the polling period length of the base or relay station allocated to the next service period, ensuring orderly transitions and preventing collisions.
2. The wireless transmission system according to claim 1 , wherein: the base station includes means for transferring a synchronization packet to a first relay station which is in a layer lower than a layer of the base station; the first relay station which has received the synchronization packet includes means for transferring the synchronization packet to a second relay station which is in a layer lower than a layer of the first relay station; and the base station and the first and second relay stations include means for determining the service periods allocated based on transmission timings of the synchronization packet.
This wireless system, as described in the initial setup, uses a base station to transfer a synchronization packet to a first-layer relay station. This relay station then transfers the synchronization packet to a second-layer relay station. The base station and the first and second relay stations determine their allocated service periods based on the transmission timings of these synchronization packets. This ensures a time-synchronized communication framework across all network nodes.
3. A wireless transmission system comprising: a base station; a plurality of relay stations; and a plurality of terminals as wireless stations, the terminals and the relay stations being wirelessly connected to the base station or the relay stations at multiple stages, wherein: the base station and the relay stations are synchronized, and a system cycle of the base station and a system cycle of the relay stations are the same in terms of time; one or more service periods are allocated in time division to the base station and the relay stations in the single system cycle; the base station or each of the relay stations includes means for performing polling communication with the terminal registered in own station with the use of polling in the single service period; in the polling communication, the base station or the relay station transmits a polling packet to the terminal registered in the own station, and the base station or the relay station includes means for receiving a reply signal from the terminal registered in the own station; the base station includes means for transferring a synchronization packet to a first relay station which is in a layer lower than a layer of the base station; the first relay station which has received the synchronization packet includes means for transferring the synchronization packet to a second relay station which is in a layer lower than a layer of the first relay station; the base station and the first and second relay stations include means for determining the service periods allocated based on transmission timings of the synchronization packet and the service period is managed by at least three parameters, including a start time of the service period, a stop time of the service period, and an entire system cycle on the basis of the transmission timing of the synchronization packet.
A wireless system features a base station, relay stations, and terminals, connected wirelessly in multiple hops. The base and relay stations are synchronized to the same system cycle. Each base or relay station gets its own time-divided service period within the cycle, using polling communication in its service period by sending polling packets to its registered terminals and receiving replies. Synchronization packets are transferred from the base station to a first-layer relay, then to a second-layer relay. Service periods are allocated based on the synchronization packet's transmission timing and managed using at least three parameters: the service period's start time, stop time, and the entire system cycle based on the synchronization packet's timing.
4. The wireless transmission system according to claim 1 , wherein: the service period has a polling period and a CSMA period; in the polling period in which the polling communication is performed, the base station or the relay station to which the service period is allocated is wirelessly connected, and polling is performed on the terminal which needs QoS communication; and in the CSMA period, the polling communication is not performed or another communication is performed.
The service period within the wireless communication system described previously is further divided into a polling period and a CSMA (Carrier Sense Multiple Access) period. The polling period is dedicated to polling communication with terminals requiring QoS (Quality of Service). During the CSMA period, polling is either suspended, or another type of communication occurs. This allows for flexible allocation of communication resources based on the specific needs of the connected terminals, optimizing throughput and prioritizing latency-sensitive data.
5. A wireless transmission system comprising: a base station; a plurality of relay stations; and a plurality of terminals as wireless stations, the terminals and the relay stations being wirelessly connected to the base station or the relay stations at multiple stages, wherein: the base station and the relay stations are synchronized, and a system cycle of the base station and a system cycle of the relay stations are the same in terms of time; one or more service periods are allocated in time division to the base station and the relay stations in the single system cycle; the base station or each of the relay stations includes means for performing polling communication with the terminal registered in own station with the use of polling in the single service period; in the polling communication, the base station or the relay station transmits a polling packet to the terminal registered in the own station, and the base station or the relay station includes means for receiving a reply signal from the terminal registered in the own station; the service period has a polling period and a CSMA period; in the polling period in which the polling communication is performed, the base station or the relay station to which the service period is allocated is wirelessly connected, and polling is performed on the terminal which needs QoS communication; in the CSMA period, the polling communication is not performed or another communication is performed; and the polling period has an exhaustive polling period in which the polling is performed on all the terminals wirelessly connected to the base station or the relay station, and a selective polling period in which the polling is performed until data is successfully transmitted from the base station or the relay station to the terminal to which the data has been unsuccessfully transmitted in a period of the exhaustive polling period.
In this wireless system composed of a base station, relays, and terminals connected wirelessly with synchronized system cycles, each base or relay station gets its own time-divided service period. Polling communication happens within this period using polling packets and replies. This service period is divided into a polling period and a CSMA period. During the polling period, stations poll terminals needing QoS. The CSMA period either stops polling or allows other communications. The polling period has an exhaustive polling period, where all connected terminals are polled, and a selective polling period, where only terminals with previously failed data transmissions are polled until successful transmission occurs.
6. The wireless transmission system according to claim 1 , wherein: two or more of the service periods are allocated to the same base station or the same relay station in the system cycle; and a first service period has an exhaustive polling period and a second service period has at least a selective polling period.
In the wireless communication system, as initially defined, two or more service periods can be allocated to the same base station or relay station within a single system cycle. The first service period uses exhaustive polling, while a second service period uses at least selective polling. This provides flexible scheduling, allowing the same station to prioritize certain terminals (exhaustive polling) and then focus on re-transmitting data to terminals that had initial transmission failures (selective polling) all within the same system cycle.
7. The wireless transmission system according to claim 1 , wherein: the relay stations include a first relay station in a first layer and a second relay station in a second layer which is lower than the first layer; and the service periods are sequentially allocated to the second relay station, the first relay station, and the base station in this order from the head of the system cycle in terms of time.
In the described wireless system, the relay stations are arranged in layers. There is a first-layer relay station and a second-layer relay station below it. The service periods within the system cycle are allocated in this order: first to the second-layer relay, then to the first-layer relay, and finally to the base station. This staggered timing approach optimizes data flow from the terminals to the base station, potentially reducing latency or improving overall throughput by prioritizing lower-level relays closer to the terminals.
8. The wireless transmission system according to claim 2 , wherein: the base station and the relay stations include means for causing the synchronization packet to have information on a synchronization reference point; and the second relay station which receives the synchronization packet includes means for holding a counter difference between internal clocks of the second relay station and the base station or the first relay station and obtaining an accurate time of the reference point on the basis of the information on the reference point and the counter difference between the internal clocks.
Building upon the multi-hop wireless system with synchronized base and relay stations, as previously specified, the base and relay stations embed synchronization reference point information within the synchronization packets. A second-layer relay station, upon receiving a synchronization packet, determines the counter difference between its internal clock and the clocks of either the base station or the first-layer relay. Using this clock difference and the reference point information, the second-layer relay can accurately determine the true time of the reference point, ensuring precise time synchronization across all network components.
9. The wireless transmission system according to claim 1 , wherein the relay station includes means for holding a table having routing information, means for receiving an association request in the relay station from a terminal which is not connected to the relay station and adding information on the terminal to information on the terminals in the routing table, means for wirelessly transferring change information of the routing table to the base station which is in a layer upper than a layer of the relay station or another relay station which is in a layer upper than the layer of the relay station, and means for receiving a bandwidth request from the terminal and wirelessly transferring the bandwidth request to the base station which is in the layer upper than a layer of the terminal or the relay station which is in the layer upper than the layer of the terminal.
This wireless system's relay stations maintain a routing table. When a new terminal associates with a relay, the relay adds the terminal's information to its routing table. The relay then wirelessly transmits the updated routing table information to the base station or another relay in an upper layer. Also, the relay stations handle bandwidth requests from their terminals and forward these requests wirelessly to either the base station or a relay in an upper layer. This allows for dynamic network management and resource allocation based on terminal connectivity and bandwidth needs.
10. The wireless transmission system according to claim 9 , wherein the relay station includes means for receiving the routing table change information from a relay station which is in a layer lower than the layer of the relay station and updating the routing table on the basis of the change information, and means for receiving the bandwidth request transferred from the relay station which is in the lower layer and transferring bandwidth request information to the base station which is in the layer upper than the layer of the relay station which is in the lower layer or the relay station which is in the layer upper than the layer of the relay station which is in the lower layer.
The wireless relay stations described above also receive routing table changes from relays in lower layers and update their own routing tables accordingly. Furthermore, they receive bandwidth requests that have been forwarded from lower-layer relays and then pass those bandwidth requests along to the base station or to a relay in a higher layer. This establishes a hierarchical system for managing routing and bandwidth allocation where changes and requests are propagated upwards through the network.
11. The wireless transmission system according to claim 9 , wherein: the base station includes means for receiving the change information on the routing table from the relay station which is in the lower layer and updating the routing table on the basis of the change information; and the base station includes means for receiving the bandwidth request transferred from the relay station which is in the lower layer, calculating a resource in response to the request, and, on the basis of a result of the calculation, transmitting, to the relay station which is in the lower layer, a packet having request permission information or request non-permission information and service period allocation change information.
In this wireless system, the base station receives routing table change information from lower-layer relay stations and updates its own routing table. Upon receiving a bandwidth request forwarded from a relay, the base station calculates the necessary resources and then transmits a packet back to the requesting relay. This packet contains either permission or denial information for the request, along with any necessary service period allocation change information based on the outcome of the base station's resource calculation. The base station centralizes resource control.
12. The wireless transmission system according to claim 9 , comprising: means for detecting disconnection of the connected terminal and updating the information on the terminal of the routing table in a case where the disconnection is confirmed; means for transferring the change information of the routing table to the base station or the relay station which is in the upper layer; and means for transferring the bandwidth request to the base station or the relay station which is in the upper layer.
Within the described wireless system, relay stations detect disconnections of connected terminals and update their routing tables accordingly. Once a disconnection is confirmed and the routing table updated, the relay station forwards these routing table changes to the base station or to a relay in a higher layer. The relay station also forwards any bandwidth requests towards the base station or higher-layer relay. This provides real-time routing and bandwidth management by reacting to changes in network topology.
13. The wireless transmission system according to claim 12 , wherein: the relay station includes means for receiving the routing table change information from a relay station which is in a lower layer and updating the routing table on the basis of the change information; and the relay station receives the bandwidth request transferred from another relay station which is in a layer lower than the layer of the relay station, and the relay station includes means for transferring the bandwidth request to the base station which is in the layer upper than the layer of the relay station or another relay station which is in a layer upper than the layer of the relay station.
The relay stations receive updated routing information from relays in lower layers, which allows each relay to update its routing table with the latest network topology. The relay station also receives bandwidth requests that have been passed up from lower-layer relays. After receiving the bandwidth request from the lower layer, the relay station then forwards the bandwidth request toward the base station or to another relay located in a higher layer. This ensures all data is correctly routed by having an accurate view of active nodes.
14. The wireless transmission system according to claim 13 , wherein: the base station includes means for receiving the change information on the routing table from the relay station which is in the layer lower than the layer of the base station and updating the routing table on the basis of the change information; and the base station includes means for receiving the bandwidth request transferred from the relay station which is in the lower layer, calculating a resource in response to the request, and, on the basis of a result of the calculation, transmitting, to the relay station which is in the lower layer, a packet having request permission and service period allocation change information.
In this wireless system, the base station receives updated routing information from lower-layer relays. The base station uses this information to keep its routing table up to date. The base station also handles bandwidth requests forwarded by relays. Upon receiving a bandwidth request, the base station calculates how to allocate resources to satisfy the request. Finally, it sends a packet to the originating relay with a request permission indicator and any service period allocation changes related to the granted resources.
15. The wireless transmission system according to claim 1 , wherein the base station collectively perform routing control, resource control, and communication timing control related to wireless communication among the base station, the plurality of relay stations, and the plurality of terminals.
In this multi-hop wireless system, the base station manages routing, resource allocation, and communication timing for all devices - the base station itself, the relay stations, and the terminals. This central control means the base station handles all aspects of network organization, ensuring efficient and robust wireless communication between all elements within the system.
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March 8, 2013
August 1, 2017
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